1. Field of the Invention
The present invention relates to wheelchairs and other wheeled apparatuses having other than solely linear wheel arrays.
2. Background Information
Because wheelchairs must obviously have a high degree of stability for remaining upright when, for example, their users traverse sloped surfaces or effect rapid turns, traditional wheelchairs with fixed wheelbase dimensions are designed with suitably large wheelbase dimensions. A wheelchair with fixed wheelbase dimensions is an impediment to wheelchair users in many contexts. For example, maneuvering into small washrooms, around cramped office quarters, and through interior doors of most homes often makes access impossible. According to a survey by "Independent Living", it costs an average of $8000 to make an average home wheelchair accessible.
Another problem relating to excessive width of a standard wheelchair's wheelbase dimensions relates to air travel. Wheelchairs of standard dimension will not pass down an airliner aisle. This necessitates the transfer from one's regular wheelchair to one of the airline's uncomfortable and humiliating "people dollies."
These problems have been recognized, and attempts have been made to address the problem. There are, for example, wheelchairs the wheel base of which can be adjusted in width. However, such chairs as are adjustable in length and/or width are designed for incremental and semi-permanent adjustments, not for ad hoc, easily reversible, on-the-fly adjustments as for temporarily dealing with obstacles which either can only be, or can more easily be traversed by a narrower wheelchair.
There exists a need among wheelchair users (of which inventor, Richard Rogers, is one) for a wheelchair (1) which adjusts in wheelbase dimensions; and (2) is adjustable on-the-fly, by the user alone to a width no greater than the seat. Despite the hundreds of wheelchair designs on the market, or depicted in wheelchair related patents, not one appears to address these objectives in combination.
It is important to note that the design for the base of the wheelchair of the present invention has application beyond the field of wheelchairs. The novel expandable/retractable base design could be incorporated into any number of wheeled vehicles, carts, automobiles or other equipment for which it would be advantageous to provide an adjustable wheelbase, the operation of which need not affect the overlying remainder of the vehicles, etc. One example of an application of the present design which is extremely far afield of the wheelchair art would be that of an industrial crane. An expansive wheelbase is desirable for most cranes. However, the wheelbase dimensions are quite limited for a vehicle-based crane which must travel by roadways. The traditional solution for providing a more stable base is to use outriggers. This, however, impedes ready movement of the crane about a work site once the outriggers are extended. Use of the subject base design would address this problem, as will be apparent following an exposition of the present design and its operation.